Nikki Haley, the US ambassador to the United Nations, has accused Russia of "cheating" international sanctions that were placed on North Korea in a bid to choke Pyongyang's nuclear and ballistic missile programmes.

During a fractious Security Council meeting on Monday, Haley said Moscow had tried to conceal "systematic" violations of the 15-member body's penalties on Pyongyang and pressure UN experts into altering a report on the implementation of the sanctions.

"Russia must cease its violations of North Korea sanctions. It must end its concerted effort to cover up evidence of sanctions violations," Haley said at the UN headquarters in New York.

Breaches included Russian assistance in ship-to-ship transfers of banned items, mainly oil but increasingly coal and other goods, she added.

A report compiled by an independent panel reviewing whether UN sanctions on Pyongyang had been implemented was submitted to the Security Council's sanctions committee in August. Russia objected to the publication of the report at the time but did not specify which parts it took issue with.

Haley said an amended version was submitted last week that removed evidence of Russian actors violating sanctions. She added that the US blocked the publication of the "tainted" report and demanded the release of the initial version.

But Vassily Nebenzia, Russia's UN ambassador, said Moscow insisted on having the report amended as it had become "hostage to the vision of Washington" and did not take into account Russia's views.

"Unsurprisingly, therefore, we insisted on having our position reflected in the document," he said, adding that the report determined that a specific ship-to-ship transfer of fuel by a Russian ship cited by Haley was not a violation.

Al Jazeera's James Bays, reporting from the UN headquarters, said the spat marked a rare departure from the Security Council's seemingly united response to North Korea in recent years.

"We have seen a lot of division on many issues between the US and Russia in the Security Council, [but] North Korea had been one rare part of the agenda where there was unity. It seems there is no longer unity," Bays said.

The Security Council has voted unanimously to ratchet up penalties on Pyongyang several times since 2006, with the most recent bout of sanctions rolled out last December.

The measures included a ban on nearly 90 percent of refined petroleum exports to North Korea and an order to its nationals working abroad to return to the country within 24 months.

Denuclearisation efforts

Monday's meeting, called for by the US, came on the eve of a high-stakesinter-Korean summit in Pyongyang.

South Korean President Moon Jae-in will travel to the North Korean capital on Tuesday for talks with the North's leader, Kim Jong-un, in what will be their third meeting this year.

Tensions between the two countries have eased in recent times, prompting hopes of peace on theKorean Peninsula, which has been divided since the 1950-53 Korean War. The two Koreas are technically still at war because their conflict ended with an armistice and not a peace treaty.

The US, which backed South Korea during the conflict, has stationed combat troops on the peninsula since the war ended and established a so-called nuclear deterrence umbrella in the region.

More than 24,000 US troops are stationed in South Korea, according to Department of Defense figures from 2016.

In June, US President Donald Trump met Kim at a landmark summit in Singapore, at which the North Korean leader pledged to "work towards complete denuclearisation" of the peninsula in a bid to "build a lasting and stable peace".

Talks between Washington and Pyongyang have stalled in recent weeks, however, with Trump accusing North Korea of making insufficient progress on the terms discussed.

In August, Trump requested Secretary of State Mike Pompeo cancel a diplomatic visit to Pyongyang over the issue.

"The continuation and further development of the DPRK's nuclear programme and related statements by the DPRK are a cause for grave concern," International Atomic Energy Agency chief Yukiya Amano said in the report, referring to North Korea's official name - the Democratic People's Republic of Korea.